This invention pertains to an automatic machine for drilling desired patterns of holes of desired diameters, especially in sheet-like members of metal or otherwise and, more particularly, but without restriction thereto, for drilling precise patterns of holes of desired different diameters in circuit boards for electronic purposes.
So-called gang drills for simultaneously drilling a plurality of holes in various objects have been in existence for a long period of time, especially for eliminating the time required to drill individual holes by powered drills or otherwise.
An early example of a so-called turret-type drill head is the subject of prior U.S. Pat. No. 463,790, dated 1891, and in which six chucks for bits are mounted radially upon a base support and are rotatable to dispose a selected drill bit in drilling position relative to a workpiece.
A more recent turret-type drill head is the subject of prior U.S. Pat. No. 3,296,896, dated Jan. 10, 1967, and in which the turret is supported rotatably upon a head arranged for vertical movement relative to a stationary work support by means of a long screw which is power driven.
It also has been proposed to drill a pattern of holes in a flat object by the use of a template in which a desired pattern of holes has been formed which serve as guides for locating a drilling tool bit relative to a workpiece. An example of this type of drilling device is the subject of prior U.S. Pat. No. 3,532,893, dated Oct. 6, 1970.
The prior U.S. Pat. No. 3,663,114 to Welsh et al, dated May 16, 1972, is directed to a drilling machine particularly designed to drill holes in circuit boards and in which there is a flat support for the boards and power means are shown by which the support is moved in two relatively transverse directions to dispose the boards as desired relative to a pair of vertically-movable pairs of drill bits of fixed size and, if different sizes of bits are to be used, the machine must be stopped and the bits changed. The machine operation is effected by means of a control tape.
It also has been proposed in this type of art to dispose a flat piece to be drilled in a fixed position upon a base and by means of elongated screws which are transverse to each other, drill supporting heads are movable into desired relative positions so that when the unit which supports the heads is lowered, presumably a desired pattern of holes is drilled in the flat workpiece.
Although the foregoing designated patents have been selected from an extensive field of patents showing devices capable of drilling patterns of holes in many different ways, it is believed they are sufficiently representative of the prior art to appreciate the advantages thereover of the present invention, details of which are set forth below.